8-H-i

APPENDIX 8-H. BASE CASE DISTRIBUTION OF EFFICIENCY LEVELS

TABLE OF CONTENTS

8-H.1 INTRODUCTION .................................................................................................8-H-1

8-H.2 ESTIMATE OF 2014 EFFICIENCY DISTRIBUTIONS BY EQUIPMENT 

CLASS AND EFFICIENCY LEVEL....................................................................8-H-1

8-H.3 PROJECTED MARKET SHARES FROM 2014 TO 2019 AND BEYOND.......8-H-4

8-H.3.1 Condensing Unit Market Share..............................................................................8-H-4

8-H.4 ESTIMATE OF 2019 EFFICIENCY DISTRIBUTIONS BY EQUIPMENT 

CLASS ...................................................................................................................8-H-8

LIST OF TABLES

Table 8-H.1.1 Fraction of Commercial Packaged Boiler Models in 2014 by 

Efficiency, Natural Draft Boilers...............................................................8-H-2

Table 8-H.1.2 Fraction of Commercial Packaged Boiler Models in 2014 by 

Efficiency, Mechanical Draft Boilers........................................................8-H-2

Table 8-H.1.3 Fraction of Commercial Packaged Boiler Models in 2014 by 

Efficiency Level, Natural Draft Boilers.....................................................8-H-3

Table 8-H.1.4 Fraction of Commercial Packaged Boiler Models in 2014 by 

Efficiency Level, Mechanical Draft Boilers..............................................8-H-4

Table 8-H.1.1 Base Case Distribution of Natural Draft Commercial Packaged Boiler 

Efficiency in 2019......................................................................................8-H-8

Table 8-H.1.2 Base Case Distribution of Mechanical Draft Commercial Packaged 

Boiler Efficiency in 2019...........................................................................8-H-9

LIST OF FIGURES

Figure 8-H.1.2 Historical Data and Projection of Base-Case Market Share for 

Condensing Mechanical Draft Gas-Fired Hot Water Commercial 

Packaged Boilers ≥300,000 Btu/hr and ≤2,500,000 Btu/hr.......................8-H-6

Figure 8-H.1.3 Historical Data and Projection of Base-Case Market Share for 

Condensing Mechanical Draft Gas-Fired Hot Water Commercial 

Packaged Boilers >2,500,000 Btu/hr .........................................................8-H-6

Figure 8-H.1.4 Historical Data and Projection of Base-Case Market Share for 

Condensing Mechanical Draft Oil-Fired Hot Water Commercial 

Packaged Boilers ≥300,000 Btu/hr and ≤2,500,000 Btu/hr.......................8-H-7

Figure 8-H.1.5 Historical Data and Projection of Base-Case Market Share for 

Condensing Mechanical Draft Oil-Fired Hot Water Commercial 

Packaged Boilers >2,500,000 Btu/hr .........................................................8-H-7
8-H-1

APPENDIX 8-H. BASE CASE DISTRIBUTION OF EFFICIENCY LEVELS

8-H.1 INTRODUCTION

The U.S. Department of Energy (DOE) derives base case efficiency distributions of 

efficiency levels by equipment class for commercial packaged boilers, which recognizes that 

commercial consumers already purchasing equipment at efficiencies greater than or equal to a 

prospective standard level are not impacted by the standard. This appendix describes the 

distributions.

DOE did not have access to sales data describing the actual distribution of efficiencies in 

current sales, nor was such information provided by industry for this rulemaking. As a 

consequence, DOE developed estimates of the distribution of efficiency levels for each of the 16 

commercial packaged boiler equipment classes. The distributions are based on the AirConditioning, Heating, and Refrigeration Institute (AHRI) Directory of Certified Product 

Performance obtained on the following dates: 1

• March 1, 2007

• March 3, 2008

• January 30, 2009

• January 11, 2011

• January 3, 2012

• April 1, 2013

• May 26, 2014

The AHRI Directory provides a review of efficiencies on the market for each equipment 

class. Note that the database from 2010 is not used.

8-H.2 ESTIMATE OF 2014 EFFICIENCY DISTRIBUTIONS BY 

EQUIPMENT CLASS AND EFFICIENCY LEVEL

DOE develops data about the share of models in each equipment class which are of the 

different designs based on the May 26, 2014, AHRI certification shown in Table 8-H.1.1 and 

Table 8-H.1.2.
8-H-2

Table 8-H.1.1 Fraction of Commercial Packaged Boiler Models in 2014 by Efficiency, 

Natural Draft Boilers

Efficiency SGMDHW LGMDHW SOMDHW LOMDHW SGMDST LGMDST SOMDST LOMDST

77 74.2% 33.8%

78 6.1% 62.2%

79 19.0%

80 22.6% 0.6% 2.7%

81 30.3% 1.4% 3.2%

82 40.6% 56.3% 56.0% 41.9%

83 5.2% 25.0% 12.0% 38.7%

84 1.3% 18.8% 18.0% 100.0%

85 6.0% 16.1%

86 6.0%

87 2.0%

88

89

Table 8-H.1.2 Fraction of Commercial Packaged Boiler Models in 2014 by Efficiency, 

Mechanical Draft Boilers

Efficiency SGMDHW LGMDHW SOMDHW LOMDHW SGMDST LGMDST SOMDST LOMDST

79 3.3% 5.5%

80 5.3% 49.5% 38.4%

81 6.8% 27.5% 4.1% 1.4% 6.9%

82 4.0% 3.4% 22.4% 7.7% 13.7% 32.9% 25.9%

83 5.3% 23.0% 21.4% 12.1% 37.0% 40.0% 19.0%

84 7.7% 11.2% 10.2% 22.4% 1.4% 12.9%

85 19.6% 18.0% 18.4% 14.5% 12.9% 44.8%

86 3.8% 2.2% 13.3% 38.2% 1.7%

87 3.7% 6.2% 8.2% 6.6% 1.7%

88 0.2% 5.1% 11.8%

89 0.5% 0.6% 2.6%

90 0.7%

91 0.5%

92 5.1% 5.1%

93 8.1% 10.1%

94 11.0% 15.7%

95 12.9% 1.7% 1.3%

96 2.6% 2.2% 1.0% 1.3%

97 1.5% 0.6% 1.3%

98 0.5%

99 0.1%

To create the fractions of boilers by efficiency levels, DOE uses the following criteria to 

process the AHRI model directory data:

1. Only boilers that meet the current standard are included.
8-H-3

2. Reported efficiency is rounded down to the nearest whole number. For example, 92 

percent represents reported efficiencies from 92 percent to 93 percent, including 92 

percent and excluding 93 percent.

3. Rounded efficiency from Step 2 is rounded to the nearest considered efficiency level.

4. Boilers that are listed as both hot water and steam are included in both the hot water and 

steam analysis.

Table 8-H.1.3 and Table 8-H.1.4 show the adjusted fractions of commercial packaged 

boiler models by efficiency level in 2014. The adjusted fractions are equivalent to the assumed 

distribution of commercial packaged boiler efficiency in 2014.

Table 8-H.1.3 Fraction of Commercial Packaged Boiler Models in 2014 by Efficiency 

Level, Natural Draft Boilers

Efficiency SGNDHW LGNDHW SONDHW LONDHW SGNDST LGNDST SONDST LONDST

77 74.2% 33.8%

78 15.6% 62.2%

79 1.4%

80 22.6% 10.1%

81 30.3% 2.7% 3.8%

82 45.8% 56.3% 56.0% 50.0%

83 25.0% 21.0% 46.2%

84 18.8% 100.0%

85 1.3% 18.0%

86

87 5.0%
8-H-4

Table 8-H.1.4 Fraction of Commercial Packaged Boiler Models in 2014 by Efficiency 

Level, Mechanical Draft Boilers

Efficiency SGMDHW LGMDHW SOMDHW LOMDHW SGMDST LGMDST SOMDST LOMDST

79 3.3% 5.6%

80 12.1% 49.5% 43.1%

81 31.3% 17.9% 19.8%

82 14.9% 22.4%

83 13.2% 21.4% 15.9% 51.4% 56.4% 31.9%

84 31.7% 28.6% 29.6% 19.3%

85 25.3%

86 18.0% 48.7% 6.4% 48.3%

87 6.3% 26.5%

88 17.8%

89

90

91

92 14.4%

93

94 32.6%

95 26.6%

96

97 2.8% 3.9%

98 2.1% 1.0%

8-H.3 PROJECTED MARKET SHARES FROM 2014 TO 2019 AND 

BEYOND

8-H.3.1 Condensing Unit Market Share 

DOE assumes that the condensing boiler market share will increase linearly by equipment 

class from 2014 to 2049. DOE determines the linear fit parameters based on the percent of 

condensing models in the AHRI Directory from 2007 to 2014, excluding 2010. 

From 2007 to 2009, the percent of condensing mechanical draft gas-fired hot water 

commercial packaged boilers increased by approximately 5-percent per year for small boilers 

and on average 1.1-percent per year for large boilers. From 2011 to 2014, the growth rate slows 

down to an average of approximately 1.2-percent per year for small boilers and on average 0.7 

percent per year for large boilers. DOE assumes that the growth rate from 2011 to 2014 is 

representative of the future market share of condensing mechanical draft gas-fired hot water 

commercial packaged boilers, and uses this growth rate from 2015 to 2049.

From 2007 to 2009, there were no condensing mechanical draft oil-fired hot water 

commercial packaged boilers. From 2011 to 2013, the market share of condensing models 

increased. In 2014 there is a sharp decrease in the condensing market share. DOE believes that 

the decrease is due to one or more manufacturers discontinuing a certified product line and 

subsequently coming out with a new product line that is not yet certified but likely will be. For 
8-H-5

this reason, DOE has decided to disregard the data from 2014. DOE assumes that the growth rate 

from 2009 and 2011 to 2013 is representative of the future market share of mechanical draft oilfired hot water commercial packaged boilers, and uses this growth rate from 2015 to 2049.

Figure 8-H.1.2 through Figure 8-H.1.5 plot the historical data and projections of market 

share of condensing units for mechanical draft gas-fired hot water commercial packaged boilers

≥300,000 Btu/hr and ≤2,500,000 Btu/hr, mechanical draft gas-fired hot water commercial 

packaged boilers >2,500,000 Btu/hr, mechanical draft oil-fired hot water commercial packaged 

boilers ≥300,000 Btu/hr and ≤2,500,000 Btu/hr, and mechanical draft oil-fired hot water 

commercial packaged boilers >2,500,000 Btu/hr, respectively. See appendix 7-B for the 

derivation of historical fraction of condensing boilers.
8-H-6

Figure 8-H.1.2 Historical Data and Projection of Base-Case Market Share for 

Condensing Mechanical Draft Gas-Fired Hot Water Commercial 

Packaged Boilers ≥300,000 Btu/hr and ≤2,500,000 Btu/hr

Figure 8-H.1.3 Historical Data and Projection of Base-Case Market Share for 

Condensing Mechanical Draft Gas-Fired Hot Water Commercial 

Packaged Boilers >2,500,000 Btu/hr

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

2007 2017 2027 2037 2047

Percent of Models that are 

Condensing

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

2007 2017 2027 2037 2047

Percent of Models that are 

Condensing
8-H-7

Figure 8-H.1.4 Historical Data and Projection of Base-Case Market Share for 

Condensing Mechanical Draft Oil-Fired Hot Water Commercial 

Packaged Boilers ≥300,000 Btu/hr and ≤2,500,000 Btu/hr

Figure 8-H.1.5 Historical Data and Projection of Base-Case Market Share for 

Condensing Mechanical Draft Oil-Fired Hot Water Commercial 

Packaged Boilers >2,500,000 Btu/hr

DOE assumes that the market shares of condensing steam boilers and condensing natural 

draft boilers will be negligible during the period of analysis (2019-2049). 

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

2007 2017 2027 2037 2047

Percent of Models that are 

Condensing

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

2007 2017 2027 2037 2047

Percent of Models that are 

Condensing
8-H-8

8-H.4 ESTIMATE OF 2019 EFFICIENCY DISTRIBUTIONS BY 

EQUIPMENT CLASS

DOE uses the efficiency distribution in 2009 and 2011‒2014, as well as the projections of 

the base-case market share of condensing boilers from 2014 to 2019, to project the efficiency 

distributions in 2019. The base-case distributions of condensing gas-fired and oil-fired 

mechanical draft hot water boilers in 2019 are calculated by multiplying the market shares in 

2014 with a factor that considers the increase in market share of condensing boilers from 2014-

2019. The derivation of this factor is described in section 8-H.3.1, and is different for fuel oil and 

gas. The non-condensing gas-fired and oil-fired mechanical draft hot water boilers will cover the 

rest of the market, with their shares kept in the same proportional relationship as the average 

market shares from 2009 and 2011-2014. For all steam boiler equipment classes and all natural 

draft equipment classes, DOE assumes that the base case efficiency distribution in 2015 was the 

average of the distribution from 2009 and 2011-2014. DOE assumes that the distribution 

remained constant from 2015-2019. The calculated base case distribution of commercial 

packaged boiler efficiency in 2019 is summarized in Table 8-H.1.1 and Table 8-H.1.2

Table 8-H.1.1 Base Case Distribution of Natural Draft Commercial Packaged Boiler

Efficiency in 2019

Efficiency SGNDHW LGNDHW SONDHW LONDHW SGNDST LGNDST SONDST LONDST

77 71.7% 21.1%

78 17.1% 44.3%

79 21.8%

80 16.0% 11.3%

81 16.5% 12.8% 48.1%

82 62.4% 78.7% 55.4% 41.1%

83 18.5% 20.3% 10.8%

84 2.8% 51.3%

85 5.1% 17.9% 29.5%

86 19.2%

87 6.4%
8-H-9

Table 8-H.1.2 Base Case Distribution of Mechanical Draft Commercial Packaged Boiler

Efficiency in 2019

Efficiency SGMDHW LGMDHW SOMDHW LOMDHW SGMDST LGMDST SOMDST LOMDST

79 18.6% 20.1%

80 11.8% 46.9% 42.8%

81 23.3% 31.6% 44.8%

82 16.8% 27.9%

83 12.4% 25.4% 11.2% 37.1% 53.8% 31.4%

84 30.4% 15.4% 31.3% 9.7%

85 21.7%

86 13.0% 47.7% 4.8% 23.9%

87 6.2% 22.2%

88 14.8%

89

90

91

92 15.6%

93

94 36.1%

95 26.1%

96

97 3.7% 6.2%

98 6.1% 9.0%
8-H-10

REFERENCES

1. Air Conditioning Heating and Refrigeration Institute, Consumer's Directory of Certified 

Efficiency Ratings for Heating and Water Heating Equipment (AHRI Directory 

September 2013), 2013. (Posted September 2013) (Last accessed September, 2013.) 

<http://www.ahridirectory.org/ahridirectory/pages/home.aspx>